In a distribution channel such as product shipping, a styroform packing material has been used for a long time for packing commodity and industrial products. Although the styroform package material has a merit such as a good thermal insulation performance and a light weight, it has also various disadvantages: recycling the styroform is not possible, soot is produced when it burns, a flake or chip comes off when it is snagged because of it's brittleness, an expensive mold is needed for its production, and a relatively large warehouse is necessary to store it.
Therefore, to solve such problems noted above, other packing materials and methods have been proposed. One method is a fluid container of sealingly containing a liquid or gas such as air (hereafter “air-packing device”). The air-packing device has excellent characteristics to solve the problems involved in the styroform. First, because the air-packing device is made of only thin sheets of plastic films, it does not need a large warehouse to store it unless the air-packing device is inflated. Second, a mold is not necessary for its production because of its simple structure. Third, the air-packing device does not produce a chip or dust which may have adverse effects on precision products. Also, recyclable materials can be used for the films forming the air-packing device. Further, the air-packing device can be produced with low cost and transported with low cost.
FIG. 1 shows an example of structure of an air-packing device in the conventional technology. The air-packing device 10a is composed of first and second thermoplastic films 13–14 and a check valve 11. Typically, each of the thermoplastic films 13–14 is composed of three layers of materials: polyethylene, nylon and polyethylene which are bonded together with appropriate adhesive. The first and second thermoplastic films 13–14 are heat-sealed together around rectangular edges (heat-seal portions) 12a, 12b after the check valve 11 is attached. Thus, one container bag 10a heat-sealed at the heat seal portions 12a, 12b is formed such as shown in FIG. 1.
FIGS. 2A–2B show another example of an air-packing device 10b with multiple air containers where each air container is provided with a check valve. A main purpose of having multiple air containers is to increase the reliability, because each air container is independent from the others. Namely, even if one of the air containers suffers from an air leakage for some reason, the air-packing device can still function as a shock absorber for packing the product because other air containers are intact.
In FIG. 2A, the air-packing device 10b is made of the first and second thermoplastic films noted above which are bonded together at a rectangular periphery 23a and further bonded together at each boundary 23b between two air containers 22 so that a guide passage 21 and two or more air containers 22 are created. When the first and second thermoplastic container films are bonded together, as shown in FIG. 2A, the check valves 11 are also attached to each inlet port of the air container 22. By attaching the check valves 11, each air container 22 becomes independent from the others. The inlet port 24 of the air-packing device 10b is used for filling an air to each air container 22 by using, for example, an air compressor.
FIG. 2B shows an example of the air-packing device 10b with multiple check valves when it is filled with the air. First, each air container 22 is filled with the air from the inlet port 24 through the guide passage 21 and the check valve 11. Typically, to avoid a rupture of the air containers 22 by variations in the environmental temperature, the air supplied to the air-packing device 10b is stopped when the air container 22 is inflated at about 90% of its full expansion rate. Typically, the air compressor has a gauge to monitor the supplied air pressure, and automatically stops supplying the air to the air-packing device 10b when the pressure reaches a predetermined value.
After filling the air, the expansion of each air container 22 is maintained because each check-valve 11 prevents the reverse flow of the air. The check valve 11 is typically made of two rectangular thermoplastic valve films which are bonded together to form an air pipe. The air pipe has a tip opening and a valve body to allow the air flowing through the air pipe from the tip opening but the valve body prevents the reverse air flow.
Air-packing devices are becoming more and more popular because of the advantages noted above. However, there is an increasing need to store and carry precision products or articles which are sensitive to shocks and impacts often involved in shipment of the products. For example, a personal computer such as a laptop computer includes a hard disc as a main data storage. Since the hard disc is a mechanical device with high precision, it must be protected from a shock, vibration, or other impact involved in the product distribution flow. There are many other types of product, such as wine bottles, DVD drivers, music instruments, glass or ceramic wares, etc. that need special attention so as not to receive a shock, vibration or other mechanical impact. Thus, there is a strong demand for air-packing devices that can minimize the amount of impact to the product when the product in a container box is dropped, collided or bumped against a wall, etc.